First you need to download the URL (as text):
private static String readUrl(String urlString) throws Exception {
BufferedReader reader = null;
try {
URL url = new URL(urlString);
reader = new BufferedReader(new InputStreamReader(url.openStream()));
StringBuffer buffer = new StringBuffer();
int read;
char[] chars = new char[1024];
while ((read = reader.read(chars)) != -1)
buffer.append(chars, 0, read);
return buffer.toString();
} finally {
if (reader != null)
reader.close();
}
}
Then you need to parse it (and here you have some options).
GSON (full example):
static class Item {
String title;
String link;
String description;
}
static class Page {
String title;
String link;
String description;
String language;
List<Item> items;
}
public static void main(String[] args) throws Exception {
String json = readUrl("http://www.javascriptkit.com/"
+ "dhtmltutors/javascriptkit.json");
Gson gson = new Gson();
Page page = gson.fromJson(json, Page.class);
System.out.println(page.title);
for (Item item : page.items)
System.out.println(" " + item.title);
}
Outputs:
javascriptkit.com
Document Text Resizer
JavaScript Reference- Keyboard/ Mouse Buttons Events
Dynamically loading an external JavaScript or CSS file
Try the java API from json.org:
try {
JSONObject json = new JSONObject(readUrl("..."));
String title = (String) json.get("title");
...
} catch (JSONException e) {
e.printStackTrace();
}
I use java 1.8 with com.fasterxml.jackson.databind.ObjectMapper
ObjectMapper mapper = new ObjectMapper();
Integer value = mapper.readValue(new URL("your url here"), Integer.class);
Integer.class can be also a complex type. Just for example used.
import org.apache.commons.httpclient.util.URIUtil;
import org.apache.commons.io.FileUtils;
import groovy.json.JsonSlurper;
import java.io.File;
tmpDir = "/defineYourTmpDir"
URL url = new URL("http://yourOwnURL.com/file.json");
String path = tmpDir + "/tmpRemoteJson" + ".json";
remoteJsonFile = new File(path);
remoteJsonFile.deleteOnExit();
FileUtils.copyURLToFile(url, remoteJsonFile);
String fileTMPPath = remoteJsonFile.getPath();
def inputTMPFile = new File(fileTMPPath);
remoteParsedJson = new JsonSlurper().parseText(inputTMPFile.text);
GSON has a builder that takes a Reader object: fromJson(Reader json, Class classOfT).
This means you can create a Reader from a URL and then pass it to Gson to consume the stream and do the deserialisation.
Only three lines of relevant code.
import java.io.InputStreamReader;
import java.net.URL;
import java.util.Map;
import com.google.gson.Gson;
public class GsonFetchNetworkJson {
public static void main(String[] ignored) throws Exception {
URL url = new URL("https://httpbin.org/get?color=red&shape=oval");
InputStreamReader reader = new InputStreamReader(url.openStream());
MyDto dto = new Gson().fromJson(reader, MyDto.class);
// using the deserialized object
System.out.println(dto.headers);
System.out.println(dto.args);
System.out.println(dto.origin);
System.out.println(dto.url);
}
private class MyDto {
Map<String, String> headers;
Map<String, String> args;
String origin;
String url;
}
}
If you happen to get a 403 error code with an endpoint which otherwise works fine (e.g. with
curl
or other clients) then a possible cause could be that the endpoint expects aUser-Agent
header and by default Java URLConnection is not setting it. An easy fix is to add at the top of the file e.g.System.setProperty("http.agent", "Netscape 1.0");
.
You could use org.apache.commons.io.IOUtils for downloading and org.json.JSONTokener for parsing:
JSONObject jo = (JSONObject) new JSONTokener(IOUtils.toString(new URL("http://gdata.youtube.com/feeds/api/videos/SIFL9qfmu5U?alt=json"))).nextValue();
System.out.println(jo.getString("version"));
public static TargetClassJson downloadPaletteJson(String url) throws IOException {
if (StringUtils.isBlank(url)) {
return null;
}
String genreJson = IOUtils.toString(new URL(url).openStream());
return new Gson().fromJson(genreJson, TargetClassJson.class);
}
Here is a easy method.
First parse the JSON from url -
public String readJSONFeed(String URL) {
StringBuilder stringBuilder = new StringBuilder();
HttpClient httpClient = new DefaultHttpClient();
HttpGet httpGet = new HttpGet(URL);
try {
HttpResponse response = httpClient.execute(httpGet);
StatusLine statusLine = response.getStatusLine();
int statusCode = statusLine.getStatusCode();
if (statusCode == 200) {
HttpEntity entity = response.getEntity();
InputStream inputStream = entity.getContent();
BufferedReader reader = new BufferedReader(
new InputStreamReader(inputStream));
String line;
while ((line = reader.readLine()) != null) {
stringBuilder.append(line);
}
inputStream.close();
} else {
Log.d("JSON", "Failed to download file");
}
} catch (Exception e) {
Log.d("readJSONFeed", e.getLocalizedMessage());
}
return stringBuilder.toString();
}
Then place a task and then read the desired value from JSON -
private class ReadPlacesFeedTask extends AsyncTask<String, Void, String> {
protected String doInBackground(String... urls) {
return readJSONFeed(urls[0]);
}
protected void onPostExecute(String result) {
JSONObject json;
try {
json = new JSONObject(result);
////CREATE A JSON OBJECT////
JSONObject data = json.getJSONObject("JSON OBJECT NAME");
////GET A STRING////
String title = data.getString("");
//Similarly you can get other types of data
//Replace String to the desired data type like int or boolean etc.
} catch (JSONException e1) {
e1.printStackTrace();
}
//GETTINGS DATA FROM JSON ARRAY//
try {
JSONObject jsonObject = new JSONObject(result);
JSONArray postalCodesItems = new JSONArray(
jsonObject.getString("postalCodes"));
JSONObject postalCodesItem = postalCodesItems
.getJSONObject(1);
} catch (Exception e) {
Log.d("ReadPlacesFeedTask", e.getLocalizedMessage());
}
}
}
You can then place a task like this -
new ReadPlacesFeedTask()
.execute("JSON URL");
A simple alternative solution:
Paste the URL into a json to csv converter
Open the CSV file in either Excel or Open Office
Use the spreadsheet tools to parse the data
Source: Stackoverflow.com